Mark 13:11
But when they shall lead you, and deliver you up, take no thought beforehand what ye shall speak, neither do ye premeditate: but whatsoever shall be given you in that hour, that speak ye: for it is not ye that speak, but the Holy Ghost. But when they shall lead you, and deliver you up, take no thought beforehand what ye shall speak, neither do ye premeditate: but whatsoever shall be given you in that hour, that speak ye: for it is not ye that speak, but the Holy Ghost.
Jesus spoke these words privately on the Mount of Olives to Peter and James and John and Andrew in answer to their question about when the temple would be thrown down and destroyed and what would be the sign of fulfillment, of His coming and of the end of the world. In that answer He mingled the description of the destruction of Jerusalem with the description of the great day of His coming, in mercy blending the two great crises because the disciples could not have endured a full sight of the future, leaving them to study out the meaning for themselves. His prophetic words about Jerusalem reach beyond that event to the final conflagration when the Lord rises to punish the world for iniquity. The whole discourse was given not for the disciples only but for those who will live in the last scenes of this earth's history.
The promise applies when Christ's followers are led and delivered up to councils and synagogues and brought before authorities, rulers, kings and judges because of their faith and for His sake, after the gospel must first be published among all nations. At that time they are to take no thought beforehand, neither premeditate, plan, rehearse, worry anxiously, nor prepare a set speech or defense in advance, but to speak whatsoever is given them in that hour. Their preparation is not to be a set speech for trial but daily readiness, and after faithful preparation and service they are to trust God to supply the right words when needed.
The reason is that it is not they that speak but the Holy Ghost, with God instructing and guiding them, the Spirit speaking through them and animating them as witnesses. When the Holy Spirit rules the mind, words of heavenly wisdom come to it and are recognized as God's words distinct from one's own thoughts, carrying wisdom, life and power. The Spirit brings to mind and remembrance at the very time it is needed the truths gained by diligent searching of the Scriptures that will reach the hearts of the hearers, flashing that knowledge into memory at the very moment it is required.
This promise requires daily preparation and trust rather than self-reliance or anxious preparation. That preparation is treasuring and storing the precious truths and gems of God's Word in the heart, feeding upon the teaching of Christ, obeying God, following Christ, studying the truth, serving God daily with undivided affections, and strengthening faith through prayer and tasting the power of His grace in trial. Those who neglect to fill the mind, do not acquaint themselves with the words of Christ, have never tasted the power of His grace in trial, and neglect to learn cannot expect the Spirit to bring His words to remembrance.
The words so given serve as a testimony to the persecutors and give assurance to speak the name of Jesus as Friend and Elder Brother. Brought into close communion with Christ and sitting with Him in heavenly places, with hearts surcharged with full, deep, far-reaching benevolence, with intense longing to carry forward the work He had begun and extend the triumphs of the cross, realizing the greatness of their debt to heaven and the responsibility of their work, witnesses clothe their testimony in burning language to go to the ends of the earth testifying to the power of Christ. Strengthened by the endowment of the Holy Spirit and going forth filled with zeal, with the peace of Christ shining from their faces and lives consecrated to Him for service bearing evidence of their surrender, they carry that testimony with power.
The same help equips learners with words and ability to speak when they need them for work that would otherwise exceed their abilities. God also gives words and guidance in the moment to sad, discouraged believers who are weak in faith when they go out to help someone more needy than themselves, especially by selling books, repeating helpful passages, and speaking comfort and encouragement. As they plead with the Lord He guides them to those seeking light, Christ stays close beside them teaching them what to say and do, and the Holy Spirit puts into their minds plans and methods for helping and blessing each person they meet. So in comforting others they themselves are comforted and grow strong in God's strength with assurance that they are God's helping hand.